Size: For left or right knee, measure around kneecap while in a standing position. Medium: 15.0-17.0 in (38.1-43.2 cm). When to Use: This Futuro Sport Moisture Control Knee Support provides support to stiff, weak, or injured knees. A unique combination of neoprene and Polartec Power Stretch-RX materials keeps the knee warm and limber while releasing excess heat and moisture. The contoured design and dual precision straps will help keep the support in place during sports or other vigorous activities. If discomfort or pain results, persists or increases, discontinue use and consult a physician. Washing: Close fasteners before washing. Hand wash with mild soap in warm (not hot) water. Rinse well and air dry. Do Not: machine wash, tumble dry, dry clean, or use bleach or fabric softeners. How to Wear: 1. Open all closures and slide support over foot starting with the wider end. Position patella ring over kneecap. 2. Secure top strap along top edge of support. 3. Secure bottom strap along bottom edge of support. Tighten both straps until fit is snug, yet comfortable.